1. Field of the Invention
The present invention pertains to the art of scroll fluid devices and, more particularly, to a synchronizer assembly for use in a scroll fluid device.
2. Discussion of the Prior Art
The term "scroll fluid devices" is applied to an arrangement of meshed spiralling wraps that are moved along circular translation paths in orbiting fashion relative to each other when at least one of the wraps is rotated. This orbiting motion produces one or more fluid transport chambers that move radially between inlet and outlet zones of the device. Such scroll devices may function as pumps, compressors, motors or expanders, depending upon their configuration, the drive system utilized and the nature of the energy transferred between the scroll wraps and the fluid moving through the device.
A significant advantage in the operation of a scroll fluid device can be achieved by minimizing its overall size while retaining the same sized transport chambers. Therefore, it is desirable to construct the scroll fluid device as small in diameter as possible. When using a co-rotating scroll arrangement, additional performance advantages are achieved with high speed operation. The power loss due to viscous drag and centrifugal action of the synchronizer teeth is proportional to the speed cubed and the diameter to the fifth power. Doubling the diameter of the teeth alone can result in 32 times the power loss due to windage and centrifugal pumping factors alone. In addition, the noise generated by operation of the device will increase with increased diameter. Reducing the overall diameter of the scroll device by even 25% would be of significant importance.
As is known in the art, scroll wrap pairs typically are coupled by a synchronizer mechanism in order to prevent relative rotation between the wraps while accommodating relative orbital movement therebetween. A typical example of a synchronizer for a scroll fluid device is an Oldham coupling as illustrated in U.S. Pat. No. 4,178,143 to Thelen et al.. Unfortunately, typical Oldham couplings substantially increase both the radial and axial dimensions of the scroll fluid device as well as the amount of friction incurred during operation thereof.
U.S. Pat. No. 4,927,340 to McCullough, illustrated in FIGS. 1 and 2 herein, discloses a synchronizer assembly for use in a scroll fluid device 10 that reduces the axial dimensions of the device at the expense of increasing the radial dimension thereof. The synchronizer comprises a plurality of circumferentially spaced teeth 38, carried by a first wrap support plate 20, which are interdigited with a plurality of circumferentially spaced grooves 40 formed in a second wrap support plate 22. The geometry of this configuration, however, requires that the teeth be placed a significant distance radially outwardly from the scroll wraps 12, 14 in order to ensure that the synchronizer will not interfere with the mated scrolls. Therefore, the diameter of the scroll device must be increased to accommodate this synchronizer arrangement. Other prior art scroll fluid devices having reduced axial dimensions at the expense of their radial dimensions are exemplified by U.S. Pat. Nos. 4,911,621 issued to McCullough et al. and 5,149,255 issued to Young.
Of additional concern, the synchronizer itself can create a problem with respect to the flow of fluid entering the scroll when the scroll device operates as a compressor, for example. The geometry and centrifugal pumping action of the synchronizer teeth in the scroll fluid device disclosed in the '340 Patent and other similar arrangements prevents fluid from entering the transport chamber(s) between the scroll wraps tangentially. Instead, the fluid must pass either radially or axially through the synchronizer. Operation of the scroll device acts to increase the velocity of the fluid as it enters an inlet zone associated therewith. However, the velocity of the fluid must be substantially zero by the time it enters the transport chamber, i.e., by the time the fluid is completely enclosed by the wraps. This requires a rather high velocity fluid stream to be diffused to a low velocity flow, which results is a significant power loss.
Therefore, there exists a need in the art for a synchronizer assembly for preventing relative rotation between meshed wraps of a scroll fluid device, while accommodating relative orbital motion between the wraps, which minimizes the size of the scroll fluid device without diminishing its capacity. In addition, there is a need in the art for a synchronizer device for a scroll fluid device which will permit fluid to enter the device tangentially and at a substantially reduced velocity so as to improve or optimize efficiency of the device.